Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
2056a782 | 34 | #include <linux/blktrace_api.h> |
9817064b | 35 | #include <linux/hash.h> |
0835da67 | 36 | #include <linux/uaccess.h> |
1da177e4 | 37 | |
55782138 LZ |
38 | #include <trace/events/block.h> |
39 | ||
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
9817064b JA |
45 | /* |
46 | * Merge hash stuff. | |
47 | */ | |
48 | static const int elv_hash_shift = 6; | |
49 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
50 | #define ELV_HASH_FN(sec) \ |
51 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 52 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 53 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 54 | |
da775265 JA |
55 | /* |
56 | * Query io scheduler to see if the current process issuing bio may be | |
57 | * merged with rq. | |
58 | */ | |
59 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
60 | { | |
165125e1 | 61 | struct request_queue *q = rq->q; |
b374d18a | 62 | struct elevator_queue *e = q->elevator; |
da775265 JA |
63 | |
64 | if (e->ops->elevator_allow_merge_fn) | |
65 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
66 | ||
67 | return 1; | |
68 | } | |
69 | ||
1da177e4 LT |
70 | /* |
71 | * can we safely merge with this request? | |
72 | */ | |
72ed0bf6 | 73 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
74 | { |
75 | if (!rq_mergeable(rq)) | |
76 | return 0; | |
77 | ||
e17fc0a1 DW |
78 | /* |
79 | * Don't merge file system requests and discard requests | |
80 | */ | |
7b6d91da | 81 | if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) |
e17fc0a1 DW |
82 | return 0; |
83 | ||
8d57a98c AH |
84 | /* |
85 | * Don't merge discard requests and secure discard requests | |
86 | */ | |
87 | if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) | |
88 | return 0; | |
89 | ||
1da177e4 LT |
90 | /* |
91 | * different data direction or already started, don't merge | |
92 | */ | |
93 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
94 | return 0; | |
95 | ||
96 | /* | |
da775265 | 97 | * must be same device and not a special request |
1da177e4 | 98 | */ |
bb4067e3 | 99 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
100 | return 0; |
101 | ||
7ba1ba12 MP |
102 | /* |
103 | * only merge integrity protected bio into ditto rq | |
104 | */ | |
105 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
106 | return 0; | |
107 | ||
da775265 JA |
108 | if (!elv_iosched_allow_merge(rq, bio)) |
109 | return 0; | |
1da177e4 | 110 | |
da775265 | 111 | return 1; |
1da177e4 LT |
112 | } |
113 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
114 | ||
73c10101 | 115 | int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
116 | { |
117 | int ret = ELEVATOR_NO_MERGE; | |
118 | ||
119 | /* | |
120 | * we can merge and sequence is ok, check if it's possible | |
121 | */ | |
122 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 123 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 124 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 125 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
126 | ret = ELEVATOR_FRONT_MERGE; |
127 | } | |
128 | ||
129 | return ret; | |
130 | } | |
1da177e4 | 131 | |
1da177e4 LT |
132 | static struct elevator_type *elevator_find(const char *name) |
133 | { | |
a22b169d | 134 | struct elevator_type *e; |
1da177e4 | 135 | |
70cee26e | 136 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
137 | if (!strcmp(e->elevator_name, name)) |
138 | return e; | |
1da177e4 | 139 | } |
1da177e4 | 140 | |
a22b169d | 141 | return NULL; |
1da177e4 LT |
142 | } |
143 | ||
144 | static void elevator_put(struct elevator_type *e) | |
145 | { | |
146 | module_put(e->elevator_owner); | |
147 | } | |
148 | ||
149 | static struct elevator_type *elevator_get(const char *name) | |
150 | { | |
2824bc93 | 151 | struct elevator_type *e; |
1da177e4 | 152 | |
2a12dcd7 | 153 | spin_lock(&elv_list_lock); |
2824bc93 TH |
154 | |
155 | e = elevator_find(name); | |
e1640949 | 156 | if (!e) { |
e1640949 | 157 | spin_unlock(&elv_list_lock); |
490b94be | 158 | request_module("%s-iosched", name); |
e1640949 JA |
159 | spin_lock(&elv_list_lock); |
160 | e = elevator_find(name); | |
161 | } | |
162 | ||
2824bc93 TH |
163 | if (e && !try_module_get(e->elevator_owner)) |
164 | e = NULL; | |
165 | ||
2a12dcd7 | 166 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
167 | |
168 | return e; | |
169 | } | |
170 | ||
165125e1 JA |
171 | static void *elevator_init_queue(struct request_queue *q, |
172 | struct elevator_queue *eq) | |
1da177e4 | 173 | { |
bb37b94c | 174 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 175 | } |
1da177e4 | 176 | |
165125e1 | 177 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
178 | void *data) |
179 | { | |
1da177e4 | 180 | q->elevator = eq; |
bc1c1169 | 181 | eq->elevator_data = data; |
1da177e4 LT |
182 | } |
183 | ||
484fc254 | 184 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 185 | |
5f003976 | 186 | static int __init elevator_setup(char *str) |
1da177e4 | 187 | { |
752a3b79 CE |
188 | /* |
189 | * Be backwards-compatible with previous kernels, so users | |
190 | * won't get the wrong elevator. | |
191 | */ | |
492af635 | 192 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 193 | return 1; |
1da177e4 LT |
194 | } |
195 | ||
196 | __setup("elevator=", elevator_setup); | |
197 | ||
3d1ab40f AV |
198 | static struct kobj_type elv_ktype; |
199 | ||
b374d18a | 200 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 201 | struct elevator_type *e) |
3d1ab40f | 202 | { |
b374d18a | 203 | struct elevator_queue *eq; |
9817064b JA |
204 | int i; |
205 | ||
b374d18a | 206 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
207 | if (unlikely(!eq)) |
208 | goto err; | |
209 | ||
9817064b JA |
210 | eq->ops = &e->ops; |
211 | eq->elevator_type = e; | |
f9cb074b | 212 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
213 | mutex_init(&eq->sysfs_lock); |
214 | ||
b5deef90 JA |
215 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
216 | GFP_KERNEL, q->node); | |
9817064b JA |
217 | if (!eq->hash) |
218 | goto err; | |
219 | ||
220 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
221 | INIT_HLIST_HEAD(&eq->hash[i]); | |
222 | ||
3d1ab40f | 223 | return eq; |
9817064b JA |
224 | err: |
225 | kfree(eq); | |
226 | elevator_put(e); | |
227 | return NULL; | |
3d1ab40f AV |
228 | } |
229 | ||
230 | static void elevator_release(struct kobject *kobj) | |
231 | { | |
b374d18a | 232 | struct elevator_queue *e; |
9817064b | 233 | |
b374d18a | 234 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 235 | elevator_put(e->elevator_type); |
9817064b | 236 | kfree(e->hash); |
3d1ab40f AV |
237 | kfree(e); |
238 | } | |
239 | ||
165125e1 | 240 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
241 | { |
242 | struct elevator_type *e = NULL; | |
243 | struct elevator_queue *eq; | |
bc1c1169 | 244 | void *data; |
1da177e4 | 245 | |
1abec4fd MS |
246 | if (unlikely(q->elevator)) |
247 | return 0; | |
248 | ||
cb98fc8b TH |
249 | INIT_LIST_HEAD(&q->queue_head); |
250 | q->last_merge = NULL; | |
251 | q->end_sector = 0; | |
252 | q->boundary_rq = NULL; | |
cb98fc8b | 253 | |
4eb166d9 JA |
254 | if (name) { |
255 | e = elevator_get(name); | |
256 | if (!e) | |
257 | return -EINVAL; | |
258 | } | |
1da177e4 | 259 | |
4eb166d9 JA |
260 | if (!e && *chosen_elevator) { |
261 | e = elevator_get(chosen_elevator); | |
262 | if (!e) | |
263 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
264 | chosen_elevator); | |
265 | } | |
248d5ca5 | 266 | |
4eb166d9 JA |
267 | if (!e) { |
268 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
269 | if (!e) { | |
270 | printk(KERN_ERR | |
271 | "Default I/O scheduler not found. " \ | |
272 | "Using noop.\n"); | |
273 | e = elevator_get("noop"); | |
274 | } | |
5f003976 ND |
275 | } |
276 | ||
b5deef90 | 277 | eq = elevator_alloc(q, e); |
3d1ab40f | 278 | if (!eq) |
1da177e4 | 279 | return -ENOMEM; |
1da177e4 | 280 | |
bc1c1169 JA |
281 | data = elevator_init_queue(q, eq); |
282 | if (!data) { | |
3d1ab40f | 283 | kobject_put(&eq->kobj); |
bc1c1169 JA |
284 | return -ENOMEM; |
285 | } | |
1da177e4 | 286 | |
bc1c1169 | 287 | elevator_attach(q, eq, data); |
1abec4fd | 288 | return 0; |
1da177e4 | 289 | } |
2e662b65 JA |
290 | EXPORT_SYMBOL(elevator_init); |
291 | ||
b374d18a | 292 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 293 | { |
3d1ab40f | 294 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
295 | if (e->ops->elevator_exit_fn) |
296 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
297 | e->ops = NULL; |
298 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 299 | |
3d1ab40f | 300 | kobject_put(&e->kobj); |
1da177e4 | 301 | } |
2e662b65 JA |
302 | EXPORT_SYMBOL(elevator_exit); |
303 | ||
9817064b JA |
304 | static inline void __elv_rqhash_del(struct request *rq) |
305 | { | |
306 | hlist_del_init(&rq->hash); | |
307 | } | |
308 | ||
165125e1 | 309 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
310 | { |
311 | if (ELV_ON_HASH(rq)) | |
312 | __elv_rqhash_del(rq); | |
313 | } | |
314 | ||
165125e1 | 315 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 316 | { |
b374d18a | 317 | struct elevator_queue *e = q->elevator; |
9817064b JA |
318 | |
319 | BUG_ON(ELV_ON_HASH(rq)); | |
320 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
321 | } | |
322 | ||
165125e1 | 323 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
324 | { |
325 | __elv_rqhash_del(rq); | |
326 | elv_rqhash_add(q, rq); | |
327 | } | |
328 | ||
165125e1 | 329 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 330 | { |
b374d18a | 331 | struct elevator_queue *e = q->elevator; |
9817064b JA |
332 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
333 | struct hlist_node *entry, *next; | |
334 | struct request *rq; | |
335 | ||
336 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
337 | BUG_ON(!ELV_ON_HASH(rq)); | |
338 | ||
339 | if (unlikely(!rq_mergeable(rq))) { | |
340 | __elv_rqhash_del(rq); | |
341 | continue; | |
342 | } | |
343 | ||
344 | if (rq_hash_key(rq) == offset) | |
345 | return rq; | |
346 | } | |
347 | ||
348 | return NULL; | |
349 | } | |
350 | ||
2e662b65 JA |
351 | /* |
352 | * RB-tree support functions for inserting/lookup/removal of requests | |
353 | * in a sorted RB tree. | |
354 | */ | |
796d5116 | 355 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
356 | { |
357 | struct rb_node **p = &root->rb_node; | |
358 | struct rb_node *parent = NULL; | |
359 | struct request *__rq; | |
360 | ||
361 | while (*p) { | |
362 | parent = *p; | |
363 | __rq = rb_entry(parent, struct request, rb_node); | |
364 | ||
83096ebf | 365 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 366 | p = &(*p)->rb_left; |
796d5116 | 367 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 368 | p = &(*p)->rb_right; |
2e662b65 JA |
369 | } |
370 | ||
371 | rb_link_node(&rq->rb_node, parent, p); | |
372 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 373 | } |
2e662b65 JA |
374 | EXPORT_SYMBOL(elv_rb_add); |
375 | ||
376 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
377 | { | |
378 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
379 | rb_erase(&rq->rb_node, root); | |
380 | RB_CLEAR_NODE(&rq->rb_node); | |
381 | } | |
2e662b65 JA |
382 | EXPORT_SYMBOL(elv_rb_del); |
383 | ||
384 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
385 | { | |
386 | struct rb_node *n = root->rb_node; | |
387 | struct request *rq; | |
388 | ||
389 | while (n) { | |
390 | rq = rb_entry(n, struct request, rb_node); | |
391 | ||
83096ebf | 392 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 393 | n = n->rb_left; |
83096ebf | 394 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
395 | n = n->rb_right; |
396 | else | |
397 | return rq; | |
398 | } | |
399 | ||
400 | return NULL; | |
401 | } | |
2e662b65 JA |
402 | EXPORT_SYMBOL(elv_rb_find); |
403 | ||
8922e16c TH |
404 | /* |
405 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 406 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 407 | * specific elevators. |
8922e16c | 408 | */ |
165125e1 | 409 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
410 | { |
411 | sector_t boundary; | |
8922e16c | 412 | struct list_head *entry; |
4eb166d9 | 413 | int stop_flags; |
8922e16c | 414 | |
06b86245 TH |
415 | if (q->last_merge == rq) |
416 | q->last_merge = NULL; | |
9817064b JA |
417 | |
418 | elv_rqhash_del(q, rq); | |
419 | ||
15853af9 | 420 | q->nr_sorted--; |
06b86245 | 421 | |
1b47f531 | 422 | boundary = q->end_sector; |
02e031cb | 423 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
424 | list_for_each_prev(entry, &q->queue_head) { |
425 | struct request *pos = list_entry_rq(entry); | |
426 | ||
33659ebb CH |
427 | if ((rq->cmd_flags & REQ_DISCARD) != |
428 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 429 | break; |
783660b2 JA |
430 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
431 | break; | |
4eb166d9 | 432 | if (pos->cmd_flags & stop_flags) |
8922e16c | 433 | break; |
83096ebf TH |
434 | if (blk_rq_pos(rq) >= boundary) { |
435 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
436 | continue; |
437 | } else { | |
83096ebf | 438 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
439 | break; |
440 | } | |
83096ebf | 441 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
442 | break; |
443 | } | |
444 | ||
445 | list_add(&rq->queuelist, entry); | |
446 | } | |
2e662b65 JA |
447 | EXPORT_SYMBOL(elv_dispatch_sort); |
448 | ||
9817064b | 449 | /* |
2e662b65 JA |
450 | * Insert rq into dispatch queue of q. Queue lock must be held on |
451 | * entry. rq is added to the back of the dispatch queue. To be used by | |
452 | * specific elevators. | |
9817064b JA |
453 | */ |
454 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
455 | { | |
456 | if (q->last_merge == rq) | |
457 | q->last_merge = NULL; | |
458 | ||
459 | elv_rqhash_del(q, rq); | |
460 | ||
461 | q->nr_sorted--; | |
462 | ||
463 | q->end_sector = rq_end_sector(rq); | |
464 | q->boundary_rq = rq; | |
465 | list_add_tail(&rq->queuelist, &q->queue_head); | |
466 | } | |
2e662b65 JA |
467 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
468 | ||
165125e1 | 469 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 470 | { |
b374d18a | 471 | struct elevator_queue *e = q->elevator; |
9817064b | 472 | struct request *__rq; |
06b86245 TH |
473 | int ret; |
474 | ||
488991e2 AB |
475 | /* |
476 | * Levels of merges: | |
477 | * nomerges: No merges at all attempted | |
478 | * noxmerges: Only simple one-hit cache try | |
479 | * merges: All merge tries attempted | |
480 | */ | |
481 | if (blk_queue_nomerges(q)) | |
482 | return ELEVATOR_NO_MERGE; | |
483 | ||
9817064b JA |
484 | /* |
485 | * First try one-hit cache. | |
486 | */ | |
06b86245 TH |
487 | if (q->last_merge) { |
488 | ret = elv_try_merge(q->last_merge, bio); | |
489 | if (ret != ELEVATOR_NO_MERGE) { | |
490 | *req = q->last_merge; | |
491 | return ret; | |
492 | } | |
493 | } | |
1da177e4 | 494 | |
488991e2 | 495 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
496 | return ELEVATOR_NO_MERGE; |
497 | ||
9817064b JA |
498 | /* |
499 | * See if our hash lookup can find a potential backmerge. | |
500 | */ | |
501 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
502 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
503 | *req = __rq; | |
504 | return ELEVATOR_BACK_MERGE; | |
505 | } | |
506 | ||
1da177e4 LT |
507 | if (e->ops->elevator_merge_fn) |
508 | return e->ops->elevator_merge_fn(q, req, bio); | |
509 | ||
510 | return ELEVATOR_NO_MERGE; | |
511 | } | |
512 | ||
5e84ea3a JA |
513 | /* |
514 | * Attempt to do an insertion back merge. Only check for the case where | |
515 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
516 | * afterwards. | |
517 | * | |
518 | * Returns true if we merged, false otherwise | |
519 | */ | |
520 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
521 | struct request *rq) | |
522 | { | |
523 | struct request *__rq; | |
524 | ||
525 | if (blk_queue_nomerges(q)) | |
526 | return false; | |
527 | ||
528 | /* | |
529 | * First try one-hit cache. | |
530 | */ | |
531 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
532 | return true; | |
533 | ||
534 | if (blk_queue_noxmerges(q)) | |
535 | return false; | |
536 | ||
537 | /* | |
538 | * See if our hash lookup can find a potential backmerge. | |
539 | */ | |
540 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
541 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | |
542 | return true; | |
543 | ||
544 | return false; | |
545 | } | |
546 | ||
165125e1 | 547 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 548 | { |
b374d18a | 549 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
550 | |
551 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 552 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 553 | |
2e662b65 JA |
554 | if (type == ELEVATOR_BACK_MERGE) |
555 | elv_rqhash_reposition(q, rq); | |
9817064b | 556 | |
06b86245 | 557 | q->last_merge = rq; |
1da177e4 LT |
558 | } |
559 | ||
165125e1 | 560 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
561 | struct request *next) |
562 | { | |
b374d18a | 563 | struct elevator_queue *e = q->elevator; |
5e84ea3a | 564 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
1da177e4 | 565 | |
5e84ea3a | 566 | if (next_sorted && e->ops->elevator_merge_req_fn) |
1da177e4 | 567 | e->ops->elevator_merge_req_fn(q, rq, next); |
06b86245 | 568 | |
9817064b | 569 | elv_rqhash_reposition(q, rq); |
9817064b | 570 | |
5e84ea3a JA |
571 | if (next_sorted) { |
572 | elv_rqhash_del(q, next); | |
573 | q->nr_sorted--; | |
574 | } | |
575 | ||
06b86245 | 576 | q->last_merge = rq; |
1da177e4 LT |
577 | } |
578 | ||
812d4026 DS |
579 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
580 | struct bio *bio) | |
581 | { | |
582 | struct elevator_queue *e = q->elevator; | |
583 | ||
584 | if (e->ops->elevator_bio_merged_fn) | |
585 | e->ops->elevator_bio_merged_fn(q, rq, bio); | |
586 | } | |
587 | ||
165125e1 | 588 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 589 | { |
1da177e4 LT |
590 | /* |
591 | * it already went through dequeue, we need to decrement the | |
592 | * in_flight count again | |
593 | */ | |
8922e16c | 594 | if (blk_account_rq(rq)) { |
0a7ae2ff | 595 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 596 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 597 | elv_deactivate_rq(q, rq); |
8922e16c | 598 | } |
1da177e4 | 599 | |
4aff5e23 | 600 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 601 | |
b710a480 | 602 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
603 | } |
604 | ||
26308eab | 605 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
606 | { |
607 | static int printed; | |
e3c78ca5 TH |
608 | |
609 | lockdep_assert_held(q->queue_lock); | |
610 | ||
15853af9 TH |
611 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) |
612 | ; | |
e3c78ca5 | 613 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
614 | printk(KERN_ERR "%s: forced dispatching is broken " |
615 | "(nr_sorted=%u), please report this\n", | |
616 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
617 | } | |
618 | } | |
619 | ||
f600abe2 | 620 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 621 | { |
cd43e26f MP |
622 | if (!q->elevator) |
623 | return; | |
624 | ||
e3c78ca5 | 625 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 626 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 627 | spin_unlock_irq(q->queue_lock); |
6c7e8cee | 628 | |
c9a929dd | 629 | blk_drain_queue(q, false); |
6c7e8cee JA |
630 | } |
631 | ||
f600abe2 | 632 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee | 633 | { |
e3c78ca5 | 634 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 635 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 636 | spin_unlock_irq(q->queue_lock); |
6c7e8cee JA |
637 | } |
638 | ||
b710a480 | 639 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 640 | { |
5f3ea37c | 641 | trace_block_rq_insert(q, rq); |
2056a782 | 642 | |
1da177e4 LT |
643 | rq->q = q; |
644 | ||
b710a480 JA |
645 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
646 | /* barriers are scheduling boundary, update end_sector */ | |
647 | if (rq->cmd_type == REQ_TYPE_FS || | |
648 | (rq->cmd_flags & REQ_DISCARD)) { | |
649 | q->end_sector = rq_end_sector(rq); | |
650 | q->boundary_rq = rq; | |
651 | } | |
652 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && | |
3aa72873 JA |
653 | (where == ELEVATOR_INSERT_SORT || |
654 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
655 | where = ELEVATOR_INSERT_BACK; |
656 | ||
8922e16c | 657 | switch (where) { |
28e7d184 | 658 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 659 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 660 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
661 | list_add(&rq->queuelist, &q->queue_head); |
662 | break; | |
663 | ||
664 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 665 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 666 | elv_drain_elevator(q); |
8922e16c TH |
667 | list_add_tail(&rq->queuelist, &q->queue_head); |
668 | /* | |
669 | * We kick the queue here for the following reasons. | |
670 | * - The elevator might have returned NULL previously | |
671 | * to delay requests and returned them now. As the | |
672 | * queue wasn't empty before this request, ll_rw_blk | |
673 | * won't run the queue on return, resulting in hang. | |
674 | * - Usually, back inserted requests won't be merged | |
675 | * with anything. There's no point in delaying queue | |
676 | * processing. | |
677 | */ | |
24ecfbe2 | 678 | __blk_run_queue(q); |
8922e16c TH |
679 | break; |
680 | ||
5e84ea3a JA |
681 | case ELEVATOR_INSERT_SORT_MERGE: |
682 | /* | |
683 | * If we succeed in merging this request with one in the | |
684 | * queue already, we are done - rq has now been freed, | |
685 | * so no need to do anything further. | |
686 | */ | |
687 | if (elv_attempt_insert_merge(q, rq)) | |
688 | break; | |
8922e16c | 689 | case ELEVATOR_INSERT_SORT: |
33659ebb CH |
690 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
691 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 692 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 693 | q->nr_sorted++; |
9817064b JA |
694 | if (rq_mergeable(rq)) { |
695 | elv_rqhash_add(q, rq); | |
696 | if (!q->last_merge) | |
697 | q->last_merge = rq; | |
698 | } | |
699 | ||
ca23509f TH |
700 | /* |
701 | * Some ioscheds (cfq) run q->request_fn directly, so | |
702 | * rq cannot be accessed after calling | |
703 | * elevator_add_req_fn. | |
704 | */ | |
705 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
706 | break; |
707 | ||
ae1b1539 TH |
708 | case ELEVATOR_INSERT_FLUSH: |
709 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
710 | blk_insert_flush(rq); | |
711 | break; | |
8922e16c TH |
712 | default: |
713 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 714 | __func__, where); |
8922e16c TH |
715 | BUG(); |
716 | } | |
1da177e4 | 717 | } |
2e662b65 JA |
718 | EXPORT_SYMBOL(__elv_add_request); |
719 | ||
7eaceacc | 720 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
721 | { |
722 | unsigned long flags; | |
723 | ||
724 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 725 | __elv_add_request(q, rq, where); |
1da177e4 LT |
726 | spin_unlock_irqrestore(q->queue_lock, flags); |
727 | } | |
2e662b65 JA |
728 | EXPORT_SYMBOL(elv_add_request); |
729 | ||
165125e1 | 730 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 731 | { |
b374d18a | 732 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
733 | |
734 | if (e->ops->elevator_latter_req_fn) | |
735 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
736 | return NULL; |
737 | } | |
738 | ||
165125e1 | 739 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 740 | { |
b374d18a | 741 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
742 | |
743 | if (e->ops->elevator_former_req_fn) | |
744 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
745 | return NULL; |
746 | } | |
747 | ||
165125e1 | 748 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 749 | { |
b374d18a | 750 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
751 | |
752 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 753 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 | 754 | |
c186794d | 755 | rq->elevator_private[0] = NULL; |
1da177e4 LT |
756 | return 0; |
757 | } | |
758 | ||
165125e1 | 759 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 760 | { |
b374d18a | 761 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
762 | |
763 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 764 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
765 | } |
766 | ||
165125e1 | 767 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 768 | { |
b374d18a | 769 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
770 | |
771 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 772 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
773 | |
774 | return ELV_MQUEUE_MAY; | |
775 | } | |
776 | ||
11914a53 MA |
777 | void elv_abort_queue(struct request_queue *q) |
778 | { | |
779 | struct request *rq; | |
780 | ||
ae1b1539 TH |
781 | blk_abort_flushes(q); |
782 | ||
11914a53 MA |
783 | while (!list_empty(&q->queue_head)) { |
784 | rq = list_entry_rq(q->queue_head.next); | |
785 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 786 | trace_block_rq_abort(q, rq); |
53c663ce KU |
787 | /* |
788 | * Mark this request as started so we don't trigger | |
789 | * any debug logic in the end I/O path. | |
790 | */ | |
791 | blk_start_request(rq); | |
40cbbb78 | 792 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
793 | } |
794 | } | |
795 | EXPORT_SYMBOL(elv_abort_queue); | |
796 | ||
165125e1 | 797 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 798 | { |
b374d18a | 799 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
800 | |
801 | /* | |
802 | * request is released from the driver, io must be done | |
803 | */ | |
8922e16c | 804 | if (blk_account_rq(rq)) { |
0a7ae2ff | 805 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb CH |
806 | if ((rq->cmd_flags & REQ_SORTED) && |
807 | e->ops->elevator_completed_req_fn) | |
1bc691d3 TH |
808 | e->ops->elevator_completed_req_fn(q, rq); |
809 | } | |
1da177e4 LT |
810 | } |
811 | ||
3d1ab40f AV |
812 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
813 | ||
814 | static ssize_t | |
815 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 816 | { |
3d1ab40f | 817 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 818 | struct elevator_queue *e; |
3d1ab40f AV |
819 | ssize_t error; |
820 | ||
821 | if (!entry->show) | |
822 | return -EIO; | |
823 | ||
b374d18a | 824 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
825 | mutex_lock(&e->sysfs_lock); |
826 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
827 | mutex_unlock(&e->sysfs_lock); | |
828 | return error; | |
829 | } | |
1da177e4 | 830 | |
3d1ab40f AV |
831 | static ssize_t |
832 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
833 | const char *page, size_t length) | |
834 | { | |
3d1ab40f | 835 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 836 | struct elevator_queue *e; |
3d1ab40f | 837 | ssize_t error; |
1da177e4 | 838 | |
3d1ab40f AV |
839 | if (!entry->store) |
840 | return -EIO; | |
1da177e4 | 841 | |
b374d18a | 842 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
843 | mutex_lock(&e->sysfs_lock); |
844 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
845 | mutex_unlock(&e->sysfs_lock); | |
846 | return error; | |
847 | } | |
848 | ||
52cf25d0 | 849 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
850 | .show = elv_attr_show, |
851 | .store = elv_attr_store, | |
852 | }; | |
853 | ||
854 | static struct kobj_type elv_ktype = { | |
855 | .sysfs_ops = &elv_sysfs_ops, | |
856 | .release = elevator_release, | |
857 | }; | |
858 | ||
859 | int elv_register_queue(struct request_queue *q) | |
860 | { | |
b374d18a | 861 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
862 | int error; |
863 | ||
b2d6db58 | 864 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 865 | if (!error) { |
e572ec7e | 866 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 867 | if (attr) { |
e572ec7e AV |
868 | while (attr->attr.name) { |
869 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 870 | break; |
e572ec7e | 871 | attr++; |
3d1ab40f AV |
872 | } |
873 | } | |
874 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 875 | e->registered = 1; |
3d1ab40f AV |
876 | } |
877 | return error; | |
1da177e4 | 878 | } |
01effb0d | 879 | EXPORT_SYMBOL(elv_register_queue); |
1da177e4 | 880 | |
b374d18a | 881 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
882 | { |
883 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
884 | kobject_del(&e->kobj); | |
430c62fb | 885 | e->registered = 0; |
bc1c1169 JA |
886 | } |
887 | ||
1da177e4 LT |
888 | void elv_unregister_queue(struct request_queue *q) |
889 | { | |
bc1c1169 JA |
890 | if (q) |
891 | __elv_unregister_queue(q->elevator); | |
1da177e4 | 892 | } |
01effb0d | 893 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 894 | |
2fdd82bd | 895 | void elv_register(struct elevator_type *e) |
1da177e4 | 896 | { |
1ffb96c5 | 897 | char *def = ""; |
2a12dcd7 JA |
898 | |
899 | spin_lock(&elv_list_lock); | |
ce524497 | 900 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 901 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 902 | spin_unlock(&elv_list_lock); |
1da177e4 | 903 | |
5f003976 ND |
904 | if (!strcmp(e->elevator_name, chosen_elevator) || |
905 | (!*chosen_elevator && | |
906 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
907 | def = " (default)"; |
908 | ||
4eb166d9 JA |
909 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
910 | def); | |
1da177e4 LT |
911 | } |
912 | EXPORT_SYMBOL_GPL(elv_register); | |
913 | ||
914 | void elv_unregister(struct elevator_type *e) | |
915 | { | |
83521d3e CH |
916 | struct task_struct *g, *p; |
917 | ||
918 | /* | |
919 | * Iterate every thread in the process to remove the io contexts. | |
920 | */ | |
e17a9489 AV |
921 | if (e->ops.trim) { |
922 | read_lock(&tasklist_lock); | |
923 | do_each_thread(g, p) { | |
924 | task_lock(p); | |
2d8f6131 ON |
925 | if (p->io_context) |
926 | e->ops.trim(p->io_context); | |
e17a9489 AV |
927 | task_unlock(p); |
928 | } while_each_thread(g, p); | |
929 | read_unlock(&tasklist_lock); | |
930 | } | |
83521d3e | 931 | |
2a12dcd7 | 932 | spin_lock(&elv_list_lock); |
1da177e4 | 933 | list_del_init(&e->list); |
2a12dcd7 | 934 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
935 | } |
936 | EXPORT_SYMBOL_GPL(elv_unregister); | |
937 | ||
938 | /* | |
939 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
940 | * we don't free the old io scheduler, before we have allocated what we | |
941 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 942 | * one, if the new one fails init for some reason. |
1da177e4 | 943 | */ |
165125e1 | 944 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 945 | { |
b374d18a | 946 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 947 | void *data; |
5dd531a0 | 948 | int err; |
1da177e4 | 949 | |
cb98fc8b TH |
950 | /* |
951 | * Allocate new elevator | |
952 | */ | |
b5deef90 | 953 | e = elevator_alloc(q, new_e); |
1da177e4 | 954 | if (!e) |
5dd531a0 | 955 | return -ENOMEM; |
1da177e4 | 956 | |
bc1c1169 JA |
957 | data = elevator_init_queue(q, e); |
958 | if (!data) { | |
959 | kobject_put(&e->kobj); | |
5dd531a0 | 960 | return -ENOMEM; |
bc1c1169 JA |
961 | } |
962 | ||
1da177e4 | 963 | /* |
cb98fc8b | 964 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 965 | */ |
f600abe2 | 966 | elv_quiesce_start(q); |
cb98fc8b | 967 | |
1da177e4 | 968 | /* |
bc1c1169 | 969 | * Remember old elevator. |
1da177e4 | 970 | */ |
1da177e4 LT |
971 | old_elevator = q->elevator; |
972 | ||
1da177e4 LT |
973 | /* |
974 | * attach and start new elevator | |
975 | */ | |
e3c78ca5 | 976 | spin_lock_irq(q->queue_lock); |
bc1c1169 | 977 | elevator_attach(q, e, data); |
bc1c1169 JA |
978 | spin_unlock_irq(q->queue_lock); |
979 | ||
430c62fb JA |
980 | if (old_elevator->registered) { |
981 | __elv_unregister_queue(old_elevator); | |
1da177e4 | 982 | |
430c62fb JA |
983 | err = elv_register_queue(q); |
984 | if (err) | |
985 | goto fail_register; | |
986 | } | |
1da177e4 LT |
987 | |
988 | /* | |
cb98fc8b | 989 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
990 | */ |
991 | elevator_exit(old_elevator); | |
f600abe2 | 992 | elv_quiesce_end(q); |
75ad23bc | 993 | |
4722dc52 AB |
994 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
995 | ||
5dd531a0 | 996 | return 0; |
1da177e4 LT |
997 | |
998 | fail_register: | |
999 | /* | |
1000 | * switch failed, exit the new io scheduler and reattach the old | |
1001 | * one again (along with re-adding the sysfs dir) | |
1002 | */ | |
1003 | elevator_exit(e); | |
1da177e4 LT |
1004 | q->elevator = old_elevator; |
1005 | elv_register_queue(q); | |
e3c78ca5 | 1006 | elv_quiesce_end(q); |
75ad23bc | 1007 | |
5dd531a0 | 1008 | return err; |
1da177e4 LT |
1009 | } |
1010 | ||
5dd531a0 JA |
1011 | /* |
1012 | * Switch this queue to the given IO scheduler. | |
1013 | */ | |
1014 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
1015 | { |
1016 | char elevator_name[ELV_NAME_MAX]; | |
1017 | struct elevator_type *e; | |
1018 | ||
cd43e26f | 1019 | if (!q->elevator) |
5dd531a0 | 1020 | return -ENXIO; |
cd43e26f | 1021 | |
ee2e992c | 1022 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 1023 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
1024 | if (!e) { |
1025 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1026 | return -EINVAL; | |
1027 | } | |
1028 | ||
2ca7d93b ND |
1029 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1030 | elevator_put(e); | |
5dd531a0 | 1031 | return 0; |
2ca7d93b | 1032 | } |
1da177e4 | 1033 | |
5dd531a0 JA |
1034 | return elevator_switch(q, e); |
1035 | } | |
1036 | EXPORT_SYMBOL(elevator_change); | |
1037 | ||
1038 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
1039 | size_t count) | |
1040 | { | |
1041 | int ret; | |
1042 | ||
1043 | if (!q->elevator) | |
1044 | return count; | |
1045 | ||
1046 | ret = elevator_change(q, name); | |
1047 | if (!ret) | |
1048 | return count; | |
1049 | ||
1050 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1051 | return ret; | |
1da177e4 LT |
1052 | } |
1053 | ||
165125e1 | 1054 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1055 | { |
b374d18a | 1056 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1057 | struct elevator_type *elv; |
70cee26e | 1058 | struct elevator_type *__e; |
1da177e4 LT |
1059 | int len = 0; |
1060 | ||
e36f724b | 1061 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1062 | return sprintf(name, "none\n"); |
1063 | ||
1064 | elv = e->elevator_type; | |
1065 | ||
2a12dcd7 | 1066 | spin_lock(&elv_list_lock); |
70cee26e | 1067 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1068 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1069 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1070 | else | |
1071 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1072 | } | |
2a12dcd7 | 1073 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1074 | |
1075 | len += sprintf(len+name, "\n"); | |
1076 | return len; | |
1077 | } | |
1078 | ||
165125e1 JA |
1079 | struct request *elv_rb_former_request(struct request_queue *q, |
1080 | struct request *rq) | |
2e662b65 JA |
1081 | { |
1082 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1083 | ||
1084 | if (rbprev) | |
1085 | return rb_entry_rq(rbprev); | |
1086 | ||
1087 | return NULL; | |
1088 | } | |
2e662b65 JA |
1089 | EXPORT_SYMBOL(elv_rb_former_request); |
1090 | ||
165125e1 JA |
1091 | struct request *elv_rb_latter_request(struct request_queue *q, |
1092 | struct request *rq) | |
2e662b65 JA |
1093 | { |
1094 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1095 | ||
1096 | if (rbnext) | |
1097 | return rb_entry_rq(rbnext); | |
1098 | ||
1099 | return NULL; | |
1100 | } | |
2e662b65 | 1101 | EXPORT_SYMBOL(elv_rb_latter_request); |